New analysis of Chandrayaan-1’s lunar orbital data might explain its detection of widespread surface hydrogen on the Moon

The Earth's magnetic field, shaped by the solar wind
The Earth’s magnetic field, shaped by the solar wind

One of the significant finds coming from India’s first lunar orbiter, Chandrayaan-1, was the detection of hydrogen in many places across the entire lunar surface, in places where it seemed impossible for hydrogen to be there, even if it was locked in a molecule like water.

Researchers in Hawaii now think they have found an explanation by linking that data to the Earth’s long magnetotail, formed by the solar wind pushing against the Earth’s magnetic field. The graphic to the right illustrates that process. The scientists focused on the kind of weathering processes that occurred both when the Moon was inside that tail, and when it was not.

Li and co-authors analyzed the remote sensing data that were collected by the Moon Mineralogy Mapper instrument onboard India’s Chandrayaan 1 mission between 2008 and 2009. Specifically, they assessed the changes in water formation as the Moon traversed through Earth’s magnetotail, which includes the plasma sheet.

“To my surprise, the remote sensing observations showed that the water formation in Earth’s magnetotail is almost identical to the time when the Moon was outside of the Earth’s magnetotail,” said Li. “This indicates that, in the magnetotail, there may be additional formation processes or new sources of water not directly associated with the implantation of solar wind protons. In particular, radiation by high energy electrons exhibits similar effects as the solar wind protons.”

In other words, the evidence suggests that the hydrogen signal seen by Chandrayaan-1 might have been a very temporary implacement of that hydrogen by the solar wind, which ceases during the Moon’s periodic passages through the magnetotail. The Moon’s harsh environment then causes that hydrogen to vanish, only to reappear when it is once again exposed to the solar wind.

None of this is confirmed, so some skepticism is required. If true, however, it would provide further evidence that the hydrogen signal seen at the lunar poles that scientists hope is evidence of ice in the permanently shadowed craters might be nothing of the sort, and we shall find little ice there.

New analysis strengthens evidence of water in lunar polar craters

ice signatures in lunar south pole craters

The uncertainty of science: Scientists using data from India’s Chandrayaan-1lunar orbiter today claimed that they have confirmed water in the Moon’s polar craters.

A team of scientists, led by Shuai Li of the University of Hawaii and Brown University and including Richard Elphic from NASA’s Ames Research Center in California’s Silicon Valley, used data from NASA’s Moon Mineralogy Mapper (M3) instrument to identify three specific signatures that definitively prove there is water ice at the surface of the Moon.

M3, aboard the Chandrayaan-1 spacecraft, launched in 2008 by the Indian Space Research Organization, was uniquely equipped to confirm the presence of solid ice on the Moon. It collected data that not only picked up the reflective properties we’d expect from ice, but was able to directly measure the distinctive way its molecules absorb infrared light, so it can differentiate between liquid water or vapor and solid ice.

Most of the newfound water ice lies in the shadows of craters near the poles, where the warmest temperatures never reach above minus 250 degrees Fahrenheit. Because of the very small tilt of the Moon’s rotation axis, sunlight never reaches these regions.

The image on the right shows the craters surrounding the south pole with water ice signatures, according to this new analysis.

This press release has some puzzling aspects. First, it is almost a decade since this data was gathered. Why is this suddenly reported now, just prior to the launch of Chandrayaan-2? I suspect this release has come out now to garner some PR for that new mission.

Also, there is nothing in this release that explains why these results should be considered more certain than previous results. In fact, previous data from different lunar orbits has been somewhat contradictory, suggesting a lot of uncertainty about the presence of water-ice at the lunar poles that this story does not address or alleviate in any way.

Nonetheless, this new analysis and data adds more weight to the possibility of water near the lunar poles, making that real estate a prime target for future bases. Too bad it is China that is aiming to grab this territory, while NASA wants us to circle the Moon in LOP-G, going nowhere.

Scientists using data from India’s Chandrayaan-1 space probe have detected new evidence of water inside one crater.

More water on the Moon: Scientists using data from India’s Chandrayaan-1 space probe have detected new evidence of water inside one lunar crater.

What makes this detection important is that this particular water was not placed there by the solar wind or asteroids. Its chemistry suggests it seeped upward from deep within the Moon’s interior.